Effects of unilateral superior colliculus ablation on oculomotor and vestibulo-ocular responses in the cat

Abstract

1. Unilateral lesions of the superior colliculus were made in normal cats. Following the operation, animals exhibited a typical neglect for contralateral visual space and forced circling toward the ipsilateral side. Optokinetic nystagmus was decreased for a stimulus moving toward the ipsilateral side, particularly in the temporal-to-nasal direction when the eye contralateral to the lesion was stimulated alone. -- 2. When tested in the dark, animals exhibited a strong imbalance of their vestibulo-ocular responses (VOR) to velocity steps or to sinusoidal oscillations. Rotation of the animal toward the ipsilateral side produced a VOR with a higher gain, and a shorter phase-lead than in pre-operative controls. VOR was decreased in the opposite direction to a smaller extent, however, the overall asymmetry between the two sides at the post-operative stage was about 40%. -- 3. In two animals, spontaneous nystagmus was present in the dark with the fast phase toward the ipsilateral side. -- 4. Visual suppression of VOR was abolished during ipsiversive rotation and was still present during contraversive rotation. -- 5. The effects of unilateral colliculectomy on VOR were transient. Spontaneous nystagmus disappeared in 3 days. VOR asymmetry in the dark was no longer present after 2-3 weeks. Loss of visual VOR suppression persisted for a few more days. -- 6. Superior colliculus exerts a tonic control on static and dynamic components of VOR. This control may mediate part of VOR visual modulation and provide a substitutive input for compensation of pathological VOR asymmetry.

Effects of superior colliculus ablation on the air-righting reflex in the rat

“…The animals usually recovered from the operation on postoperative day 1 (p.o.d1); they could walk, eat, drink, and rear. Unilaterally ablated rats tended to show circling to the lesioned side, as has been reported by others [25], while in the bilateral animals, some walked straight forward even to an obstacle, and some showed circling. The experiment was usually performed on p.o.d1-3.…”

Direction-Specific Disruption of Subcortical Visual Behavior and Receptive Fields in Mice Lacking the β2 Subunit of Nicotinic Acetylcholine Receptor

“…To investigate a possible neural correlate of the observed behavioral phenotypes, we examined visually-evoked response properties of individual neurons in the central visual system. We focused our study on the primary visual cortex (V1) and the superior colliculus (SC), a midbrain structure that is involved in a variety of visuomotor behaviors (Wurtz and Albano, 1980; Flandrin and Jeannerod, 1981; Freedman et al, 1996). …”

“…The SC, which is known to initiate head and eye movement in orienting behaviors (Wurtz and Albano, 1980), may also be involved in optokinetic responses. Unilateral lesions of the SC in cats and monkeys decreased or even eliminated optokinetic responses to stimuli moving along the temporal-to-nasal direction in the hemifield contralateral to the operated side (Denny-Brown, 1962; Flandrin and Jeannerod, 1981). Although the exact function of the SC in optokinetic head movement is unknown, our physiological results provide a possible neural correlate for the observed behavioral defects.…”

“…In β2−/− mice, the precise structure of retinal waves is altered during the first postnatal week (Bansal et al, 2000; McLaughlin et al, 2003; Sun et al, 2008). Consequently, their retinotopic maps are scattered in both the primary visual cortex (V1) (Cang et al, 2005) and the superior colliculus (SC) (McLaughlin et al, 2003; Chandrasekaran et al, 2005; Mrsic-Flogel et al, 2005), a midbrain structure involved in a variety of visuomotor behaviors (Wurtz and Albano, 1980; Flandrin and Jeannerod, 1981; Freedman et al, 1996). Importantly, RGCs appear unaffected in β2−/− mice, having normal ON/OFF segregation (Bansal et al, 2000), spatial resolution (Rossi et al, 2001) and direction selectivity (Elstrott et al, 2008), making these mice a useful model to study the consequences of disrupting retinotopic maps on central visual functions.…”

Mild Traumatic Brain Injury with Associated Visual System Dysfunction: Investigating Histopathology, Functional Correlates, and a Novel Therapeutic Immune Modulator

“…Visual deficits in this eye could also be due to a defect in the initiation of saccadic response, or coordinated head movements, due to loss of cells in the superior colliculus who are integral to these functions. An experiment in cats validated that unilateral ablation of the superior colliculus causes a loss of the OKN reflex in the eye contralateral to the lesion 302 . Denervation of the superior colliculus from RGC axon degeneration could result in eventual SC neuronal degeneration, a phenomenon that has been demonstrated experimentally in rats 303 , or direct effect of the blast injury might injure SC neurons on the left side of the brain, giving rise to at least part of the RE visual deficit.…”